Right auricleAn auricle is a thin-walled, ear-like flap on an atrium. This one is on the heart's right side, which is on your left when the ventral side faces you.
Left auricleThe flap of the left atrium. Its blind, pointed end lies just behind the start of the pulmonary trunk.
Right ventricleIt sends blood into the pulmonary trunk. It does not reach the tip of the heart.
Left ventricleIt pumps blood into the aorta. Its wall is much thicker than the right ventricle's, and it alone forms the apex.
ApexThe tip of the cone. It is formed entirely by the left ventricle.
Interventricular sulcusA fat-filled groove on the surface. It marks where the wall between the ventricles lies. Coronary vessels run in it.
Coronary arterySupplies blood to the heart muscle. Coronary arteries branch from the very start of the aorta.
AortaThe largest artery, leaving the left ventricle. It arches backward and carries blood to the whole body.
Brachiocephalic trunkA very large vessel rising from the arch of the aorta. It carries blood toward the head and the front legs.
Pulmonary trunkCarries blood from the right ventricle toward the lungs. It crosses in front of the aorta.
Ligamentum arteriosumFibrous band between the pulmonary trunk and the arch of the aorta. It is what remains of the ductus arteriosus, a vessel that joined the two before birth.
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Anterior vena cavaReturns blood from the front of the body to the right atrium. In a person it is called the superior vena cava.
Posterior vena cavaReturns blood from the rear of the body to the right atrium. In a person it is called the inferior vena cava.
Pulmonary veinsCarry blood back from the lungs. They open into the left atrium.
Right atriumBoth venae cavae empty into it. It passes the blood down through the tricuspid valve.
Left atriumThe pulmonary veins empty into it. It passes the blood down through the bicuspid valve.
Aortic valveA semilunar valve made of pocket-shaped cusps. It lets blood out of the left ventricle into the aorta and stops it coming back.
Tricuspid valveBlood passes from the right atrium to the right ventricle through it. It has three flaps.
Bicuspid valveThe two-flapped valve on the left side, also called the mitral valve.
Chordae tendineaeStrong strands tying each flap of a valve to a papillary muscle. The name means tendinous cords.
Papillary muscleCone-shaped muscles that stand up from the ventricle wall. The cords from the valve flaps attach to their tips.
Interventricular septumThe muscular wall that divides the right ventricle from the left.
Moderator bandA band of heart muscle in the right ventricle. It stretches from the septum to the outer wall. In cattle it is large and muscular.
How this list was compiled: Every name checked on 2026-09-30 against Septimus Sisson, The Anatomy of the Domestic Animals (2nd ed., 1914, public domain), the heart of the horse and the ox: auricles, ventricles, longitudinal grooves with their fat, coronary arteries, brachiocephalic trunk, ligamentum arteriosum, anterior and posterior vena cava, pulmonary veins, tricuspid and bicuspid valves, chordae tendineae, papillary muscles, moderator bands, https://archive.org/details/anatomyofdomesti00siss; against OpenStax, Biology 2e, section 40.1 (mammals have a four-chambered heart), https://openstax.org/books/biology-2e/pages/40-1-overview-of-the-circulatory-system; and against OpenStax, Anatomy and Physiology 2e, section 19.1 Heart Anatomy (auricle, interventricular sulcus, coronary arteries, pulmonary trunk, tricuspid and mitral valves, chordae tendineae, papillary muscles, moderator band, aortic semilunar valve, interventricular septum), https://openstax.org/books/anatomy-and-physiology-2e/pages/19-1-heart-anatomy. The names a class uses on a sheep heart (brachiocephalic artery, anterior and posterior vena cava, the ventral view and the coronal cut) were checked in F. Bohensky, Photo Manual and Dissection Guide of the Fetal Pig: With Sheep Heart, Brain, Eye (1978), read through the Internet Archive's full-text search, https://archive.org/details/photomanualdisse0000fred_u2p3. Licence: own work
The drawing: Drawn for this site on 2026-09-30 from plain geometry; nothing traced. Licence: own work
How it works
This sheep heart diagram labeled in two views shows the heart as it lies in the tray, ventral side up, and then cut open. The sheep's left is on your right, so the left ventricle is on the right of each drawing.
Read the full guide
Outside
Find the slanting groove first. The right ventricle is above and to the left of it; the left ventricle is below it and makes the apex. An auricle sits at each upper corner. At the top, the pulmonary trunk crosses in front of the aorta, and the brachiocephalic trunk rises from the aortic arch.
Cut open
The venae cavae enter the right atrium and the pulmonary veins the left. Each atrium opens into its ventricle through a valve whose flaps are tied by chordae tendineae to papillary muscles. The septum divides the ventricles, and the moderator band crosses the right one.
Not sure which side is up? The ventral side shows the slanting groove and both auricles, with the pulmonary trunk between them.
Pinch the two ventricles. The left wall is much thicker than the right.
Questions and answers
How many chambers does a sheep heart have?
Four, as in every mammal heart diagram: a right and a left atrium on top, and a right and a left ventricle below.
Is a cow heart diagram the same as a sheep heart diagram?
The parts are the same, and so are those of a goat, deer or horse heart. The hearts differ in size and shape: an ox heart is longer and more pointed than a horse's, and it has one or two small bones in it.
How is a sheep heart different from a human heart?
Very little. The main vessels have other names because a sheep stands on four legs: anterior and posterior vena cava where a person has superior and inferior. One large brachiocephalic trunk rises from the sheep's aortic arch.
What is the moderator band in a sheep heart?
A band of heart muscle that crosses the right ventricle from the septum to the outer wall. In cattle, close relatives of the sheep, it is large and muscular.